Devices such as computer systems, routers, switches, load balancers, firewalls, and the like, are commonly linked to each other in networks. These networks are configured in different ways depending on implementation-specific details such as the hardware used and the physical location of the equipment, and also depending on the particular objectives of the network. One common type of network configuration includes a number of “virtual” networks, commonly known as virtual local area networks (VLANs). A VLAN is, in essence, a logical segmentation of a physical local area network (LAN).
An advantage of VLANs is that the devices associated with a particular virtual network do not need to all be in the same physical location, yet all will appear to be on the same LAN. Prior Art FIG. 1 is a block diagram of a portion of a LAN 10 that includes a number of racks (20, 21 and 22) of computer systems (30-38) and a hierarchy of switches (11-16). Each of the computer systems 30-38 is physically wired to a respective switch (14, 15 or 16), which are each physically wired to switches 12 and 13, which in turn are physically wired to switch 11. By routing signals through the various switches, computer systems in different racks or within the same rack can communicate with each other, within certain constraints that will be explained. In addition, a signal from a remote device (not shown) can also be routed through the various switches so that the remote device can communicate with any of the devices in LAN 10, within certain constraints as well.
In the simplified example of Prior Art FIG. 1, LAN 10 is logically segmented into a VLAN 1 and a VLAN 2. VLAN 1 includes computer systems 30 and 37, and VLAN 2 includes computer systems 31 and 36. Should computer system 30 need to communicate with computer system 37, for example, a signal from computer system 30 can be routed through switch 14 to switch 16 and on to computer system 37.
For reasons such as security or privacy, communication between VLANs may not be permitted. In LAN 10, access to a particular VLAN is controlled by the switches 11-16. For example, switch 16 can be configured to forward a message from computer system 30 (VLAN 1) to computer system 37 (VLAN 1) but to not forward a message from computer system 30 (VLAN 1) to computer system 36 (VLAN 2). In a similar manner, communication from a remote device can be controlled so that the remote device can only communicate with certain devices in LAN 10. Therefore, even though VLANs can share resources such as switches, VLANs can be prevented from sharing traffic and information.
Another advantage of VLANs is that the management and cabling of groups of devices are simplified, particularly when the allocation of resources within the LAN is changed. For instance, in the simplified example of Prior Art FIG. 1, VLAN 1 may be used by one organization and VLAN 2 by another. The first organization may need more resources, while the resources of the other organization may be under-utilized. To resolve this, one of the computer systems in VLAN 2 can be reallocated to VLAN 1. This is accomplished by reconfiguring the appropriate switches instead of rewiring the LAN.
Thus, management and allocation of resources within and across VLANs are predicated on correct cabling between devices in the LAN. While every effort can be made to ensure that the network is wired correctly the first time, mistakes can still be made. For example, as a network is wired, a technician may attach a cable to a particular port (socket) of a switch, but incorrectly record the port (socket) number in a network map. Similarly, although a network map may instruct a technician to attach a cable to a particular port, the technician may inadvertently attach the cable to an incorrect port. Therefore, it remains important to verify, after the network is set up, that the network is indeed set up correctly.
However, networks of devices are often large and complex, and so verifying that network cabling is correct can be difficult and costly. Some prior art procedures for verifying proper network cabling rely on manual procedures such as visually tracing each cable from its source device to its destination device. This is slow and costly, and in some cases is not a viable procedure, because large groups of cables are often bound together into bundles, making it difficult if not impossible to visually trace a particular cable as it disappears into a bundle.
Other prior art procedures utilize a “ping” command that is issued from a source device to a target device. If the ping command is successful, it can be presumed that the cable is properly connected. However, this approach is also slow and costly, in particular when used with networks that employ hundreds of devices and thousands of cables. Furthermore, if the ping command is not successful, it remains to be determined which end of the cable is connected incorrectly. Thus, both ends of the cable need to be checked.
For these and other reasons, a method and/or system that can verify that devices in a network are properly connected physically would be of value. Embodiments of the present invention provide this and other advantages.